Compositions and methods of treatment with prodrugs of tizoxanide, an analogue or salt thereof

ABSTRACT

Prodrugs of tizoxanide, an analogue or salt thereof are disclosed. The prodrugs have an ester moiety comprising an amino acid moiety, and increase the bioavailability of the tizoxanide, an analogue or salt thereof. Compositions and methods of treating an intracellular protozoan infection, a viral infection or a cancer are also disclosed.

This application claims the benefit of U.S. Provisional Application Ser.No. 62/078,384, filed Nov. 11, 2014, which is incorporated by referenceherein.

BACKGROUND

Nitazoxanide (2-(acetolyloxy)-N-(5-nitro-2-thiazolyl)benzamide) is acompound having the following structure:

Tizoxanide is the active circulating metabolite of nitazoxanide.

The preparation and uses of nitazoxanide are disclosed, for example, inU.S. Pat. No. 3,950,351 to Rossignol.

Pharmaceutical compositions containing nitazoxanide and its metabolite,tizoxanide, were originally developed and marketed for treatingintestinal parasitic infections. However, nitazoxanide, tizoxanide andvarious analogues thereof have been shown to have activity againstvarious intracellular protozoan infections, viral infections, includinginfluenza and hepatitis, and cancers. See U.S. Pat. Nos. 8,524,278,8,124,632, 7,645,783, 7,550,493, 7,285,567, 6,117,894, 6,020,353,5,968,961, 5,965,590, 5,935,591, and 5,886,013, and U.S. applicationSer. Nos. 12/184,760, 12/656,704, 12/821,571, 12/777,383, 13/284,242,13/471,948, which are herein incorporated by reference in theirentirety.

Furthermore, nitazoxanide, tizoxanide and various analogues thereof arecapable of stimulating an immune response in subjects, which can resultin treatment or prevention of an intracellular protozoan infection, aviral infection or a cancer.

Following oral administration of nitazoxanide or mixtures ofnitazoxanide plus tizoxanide in humans, these compounds are partiallyabsorbed from the intestinal tract, and nitazoxanide is rapidlyhydrolyzed to form tizoxanide in plasma. Tizoxanide isglucurono-conjugated, and the drug is eliminated in urine and bile astizoxanide or tizoxanide glucuronide. The half-life of tizoxanide inplasma is only approximately 1.5 hours.

Given this short half-life, and the relatively low bioavailability ofnitazoxanide, tizoxanide and various analogues thereof there remains aneed for compounds having a similar activity to nitazoxanide, tizoxanideand various analogues thereof, but with greater bioavailability.

SUMMARY OF THE DISCLOSED SUBJECT MATTER

One embodiment of the invention relates to a compound represented by:

wherein R₁ through R₅ are, independently, selected from the groupconsisting of hydrogen, CN, NO₂, F, Cl, Br, I, hydroxy, alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkylalkyl, cycloalkylalkenyl,cycloalkylalkynyl, cycloalkenyl, cycloalkenylalkyl, cycloalkenylalkenyl,cycloalkenylalkynyl, alkoxy, alkenyloxy, alkynyloxy, alkoxyalkyl,alkoxyalkenyl, alkoxyalkynyl, alkenyloxyalkyl, alkenyloxyalkenyl,alkenyloxyalkynyl, alkynyloxyalkyl, alkenyloxyalkenyl,alkenyloxyalkynyl, cycloalkoxy, cycloalkylalkoxy, cycloalkylalkenyloxy,cycloalkylalkynyloxy, cycloalkenyloxy, cycloalkenylalkoxy,cycloalkenylalkenyloxy, cycloalkenylalkynyloxy, alkoxyalkylamino,hydroxyalkyl, acyl, acyloxy, aroyloxy, arylalkanoyloxy, arylalkenoyloxy,heteroaroyloxy, heteroarylalkanoyloxy, heteroarylalkenoyloxy,alkoxycarbonyl, aryloxycarbonyl, arylalkoxycarbonyl,heteroaryloxycarbonyl, heteroarylalkoxycarbonyl, alkoxycarbonyloxy,carbamoyl, carbamoyloxy, alkylamino, dialkylamino, alkylaminoalkyl,amido, alkylamido, dialkylamido, haloalkyl, perhaloalkyl, perhaloalkoxy,alkylthio, alkylthioalkyl, alkylsulfonyl, alkylsulfonylalkyl,alkenylsulfonyl, alkynylsulfonyl, cycloalkylsulfonyl,cycloalkylalkylsulfonyl, cycloalkylsulfonylalkyl,cycloalkylalkylsulfonylalkyl, arylsulfonyl, arylalkylsulfonyl,arylalkenylsulfonyl, heteroarylsulfonyl, heteroarylalkylsulfonyl,heteroarylalkenylsulfonyl, alkylsulfonamido, N,N′-dialkylsulfonamido,sulfonamidoalkyl, sulfonamidoaryl, sulfonamidoarylalkyl,sulfonamidoarylalkenyl, aryl, arylalkyl, aryloxy, arylalkoxy, arylthio,arylalkylthio, arylamino, arylalkylamino, arylalkenyl, arylalkynyl,heteroaryl, heteroarylalkyl, heteroarylalkenyl, heteroarylalkynyl,heteroaryloxy, heteroarylalkoxy, heteroarylamino, heteroarylalkylamino,heteroarylthio, heteroarylalkylthio, heteroarylalkylamino,heterocycloalkyl, heterocycloalkenyl, heterocycloalkoxy, andheterocycloalkenyloxy, any of which may be optionally substituted,

and where each of R₁ through R₅ comprises 1 to 60 atoms;

provided at least one of R₁ through R₅ is an amino acid is selected fromthe group consisting of alanine, arginine, asparagine, aspartic acid,cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine,leucine, lysine, methionine, phenylalanine, proline, serine, threonine,tryptophan, tyrosine, and valine, or a moiety represented by Formula A:

wherein R′ is selected from the group consisting of hydrogen, alkyl, anda nitrogen protecting group;

R″ is selected from the group consisting of alkyl, alkenyl, alkynyl,cycloalkyl, cycloalkylalkyl, cycloalkylalkenyl, cycloalkylalkynyl,cycloalkenyl, cycloalkenylalkyl, cycloalkenylalkenyl,cycloalkenylalkynyl;

one of R₆ and R₉ is selected from the group consisting of NO₂, F, Cl,Br, —SO₂—(C₁-C₁₀)-alkyl, —SO—(C₁-C₁₀)-alkyl, haloalkyl, perhaloalkyl,haloalkoxy, perhaloalkoxy, S(O)_(m)C(R₇R₈)_(n)CF₃, and C(R₇R₈)_(n)CF₃;and the other of R₆ and R₉ that is not selected from the group, ishydrogen;

or a pharmaceutically acceptable salt thereof.

In another embodiment, R₆ is selected from the group consisting of NO₂,F, Cl, Br, —SO₂—(C₁-C₁₀)-alkyl, —SO—(C₁-C₁₀)-alkyl, haloalkyl,perhaloalkyl, haloalkoxy, perhaloalkoxy, S(O)_(m)C(R₇R₈)_(n)CF₃, andC(R₇R₈)—CF₃, and R₉ is hydrogen, or wherein R₉ is selected from thegroup consisting of NO₂, F, Cl, Br, —SO₂—(C₁-C₁₀)-alkyl,—SO—(C₁-C₁₀)-alkyl, haloalkyl, perhaloalkyl, haloalkoxy, perhaloalkoxy,S(O)_(m)C(R₂R₈)_(n)CF₃, and C(R₇R₈)_(n)CF₃, and R₆ is hydrogen. Inanother embodiment, R₆ is selected from the group consisting of NO₂, F,Cl, Br, —SO₂—(C₁-C₁₀)-alkyl, and —SO—(C₁-C₁₀)-alkyl, and R₉ is hydrogen,or wherein R₉ is selected from the group consisting of NO₂, F, Cl, Br,—SO₂—(C₁-C₁₀)-alkyl, and —SO—(C₁-C₁₀)-alkyl, and R₆ is hydrogen. Inanother embodiment, R₆ is selected from the group consisting of NO₂ andCl, and R₉ is hydrogen, or wherein R₉ is selected from the groupconsisting of NO₂ and Cl, and R₆ is hydrogen. In another embodiment, R₉is hydrogen. In another embodiment, R₆ is hydrogen.

In another embodiment, R′ is selected from the group consisting ofhydrogen and a nitrogen protecting group, and R″ is a straight-chain,branched-chain, or cyclic unsaturated (C₁-C₁₀)-alkyl moiety.

In another embodiment, R″ is a straight-chain or branched-chain(C₁-C₅)-alkyl moiety. In another embodiment, R″ is a (C₁-C₄)-alkylmoiety. In another embodiment, R″ is a C₃₋₄-alkyl moiety, or a t-Bumoiety. In another embodiment, R′ is hydrogen.

In another embodiment, Formula A is a moiety selected from

In another embodiment, one of R₁ through R₃ is a moiety represented byFormula A, and the remaining of R₁ through R₅ are hydrogen.

In another embodiment, R₁ is a moiety represented by Formula A, and R₂through R₅ are hydrogen.

In another embodiment, R₂ is a moiety represented by Formula A, and R₁and R₃ through R₅ are hydrogen.

In another embodiment, R₃ is a moiety represented by Formula A, and R₁,R₂, R₄ and R₅ are hydrogen.

Another embodiment of the invention relates to a pharmaceuticalcomposition comprising a compound, or pharmaceutically acceptable saltthereof, of any of the preceding embodiments, and a pharmaceuticallyacceptable excipient.

In another embodiment, the pharmaceutical composition is in the form ofa solid oral dosage form.

In another embodiment, the solid oral dosage form is a tablet.

In another embodiment, the solid oral dosage form is a capsule.

Another embodiment of the invention relates to a pharmaceuticalcomposition of any of the preceding composition embodiments, wherein thepharmaceutical composition is in the form of a solid oral dosage formcomprising:

(a) a first portion comprising a first quantity of a compound of any ofclaims 1-16, or a pharmaceutically acceptable salt thereof, in acontrolled release formulation; and

(b) a second portion comprising a second quantity of a compound of anyof claims 1-16, or a pharmaceutically acceptable salt thereof, in animmediate release formulation.

Another embodiment of the invention relates to a pharmaceuticalcomposition of any of the preceding composition embodiments, wherein thepharmaceutical composition is in the form of a solid oral dosage formcomprising a quantity of a compound of any of the preceding embodimentsor a pharmaceutically acceptable salt thereof, in a controlled releaseformulation.

A pharmaceutical composition of any of the preceding compositionembodiments, wherein the pharmaceutical composition comprises one ormore diluents, disintegrants, binders, suspending agents, glidants,lubricants, or fillers.

A pharmaceutical composition of any of the preceding compositionembodiments, wherein, when the pharmaceutical composition comprises acontrolled release formulation.

A pharmaceutical composition of any of the preceding compositions sothat when ingested orally, the composition induces statisticallysignificant higher bioavailability of a derivative of the compound ofany of the preceding embodiments or the pharmaceutically acceptable saltthereof.

The pharmaceutical composition of the preceding embodiments, wherein thederivative of the compound of any of the preceding embodiments is aderivative that does not include the moiety represented by Formula A.

Another embodiment of the invention relates to a method of treating anintracellular protozoan infection, a viral infection or a cancer,comprising administering to a patient in need thereof a therapeuticallyeffective amount of a compound or composition of any of the precedingclaims.

In another embodiment, the compound of any of the compound embodimentsis administered in combination with at least one additional componentselected from the group consisting of a vaccine, an immunostimulant, aneuraminidase inhibitor, an adamantine analogue, and a recombinantsialidase fusion protein.

In another embodiment, the method is a method of treating a viralinfection in a patient in need thereof.

In another embodiment, the viral infection is influenza infection.

In another embodiment, the viral infection is caused by a virus selectedfrom H1N1, H2N2, H3N2, H5N1, H7N7, H1N2, H9N2, H7N2, H7N3, and H10N7.

In another embodiment, the viral infection is Hepatitis B.

In another embodiment, the method is a method of treating a cancer in apatient in need thereof.

In another embodiment, the cancer is leukemia.

In another embodiment, the leukemia is hairy cell leukemia or chronicmyeloid leukemia.

In another embodiment, the cancer is melanoma.

In another embodiment, the cancer is non-Hodgkin lymphoma.

In another embodiment, the cancer is renal cell carcinoma.

In another embodiment, the compound of composition is administered incombination with at least one of a vaccine, an immunostimulant and ananticancer drug.

In another embodiment, the compound of composition is administered incombination with at least one anticancer drug is selected from the groupconsisting of STI571, CGP 74588, 1-β-D-Arabinofuranosylcytosine (Ara-C),doxorbicin, dacarbazine, cisplatin, bleomycin, vincristine, lomustine,vinblastine, carmustine, DTIC, tamoxifen, sunitinib, sorafenib andinterferon-α.

In another embodiment, the method is a method of treating anintracellular protozoan infection in a patient in need thereof.

A method of increasing the bioavailability of a thiazolide compoundcomprising administering a compound, or salt thereof, of any ofproceeding compound embodiments, to a mammal, wherein thebioavailability is increased in relation to administration ofnitazoxanide.

DETAILED DESCRIPTION

Introduction

Before the present invention is described in greater detail, it is to beunderstood that this invention is not limited to particular embodimentsdescribed, as such may, of course, vary. It is also to be understoodthat the terminology used herein is for the purpose of describingparticular embodiments only, and is not intended to be limiting, sincethe scope of the present invention will be limited only by the appendedclaims.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the invention. The upper and lowerlimits of these smaller ranges may independently be included in thesmaller ranges and are also encompassed within the invention, subject toany specifically excluded limit in the stated range. Where the statedrange includes one or both of the limits, ranges excluding either orboth of those included limits are also included in the invention.

Certain ranges are presented herein with numerical values being precededby the term “about”. The term “about” is used herein to provide literalsupport for the exact number that it precedes, as well as a number thatis near to or approximately the number that the term precedes. Indetermining whether a number is near to or approximately a specificallyrecited number, the near or approximating unrecited number may be anumber which, in the context in which it is presented, provides thesubstantial equivalent of the specifically recited number.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although any methods andmaterials similar or equivalent to those described herein can also beused in the practice or testing of the present invention, representativeillustrative methods and materials are now described.

All publications and patents cited in this specification are hereinincorporated by reference as if each individual publication or patentwere specifically and individually indicated to be incorporated byreference and are incorporated herein by reference to disclose anddescribe the methods and/or materials in connection with which thepublications are cited. The citation of any publication is for itsdisclosure prior to the filing date and should not be construed as anadmission that the present invention is not entitled to antedate suchpublication by virtue of prior invention. Further, the dates ofpublication provided may be different from the actual publication dateswhich may need to be independently confirmed.

It is noted that, as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include plural referents unless thecontext clearly dictates otherwise. It is further noted that the claimsmay be drafted to exclude any optional element. As such, this statementis intended to serve as antecedent basis for use of such exclusiveterminology as “solely”, “only” and the like in connection with therecitation of claim elements, or use of a “negative” limitation.

As will be apparent to those of skill in the art upon reading thisdisclosure, each of the individual embodiments described and illustratedherein has discrete components and features which may be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope or spirit of the presentinvention. Any recited method can be carried out in the order of eventsrecited or in any other order which is logically possible.

By “pharmaceutically acceptable” is meant a material that is notbiologically or otherwise undesirable, i.e., the material may beincorporated into a pharmaceutical composition administered to a patientwithout causing any undesirable biological effects or interacting in adeleterious manner with any of the other components of the compositionin which it is contained. When the term “pharmaceutically acceptable” isused to refer to a pharmaceutical carrier or excipient, it is impliedthat the carrier or excipient has met the required standards oftoxicological and manufacturing testing or that it is included on theInactive Ingredient Guide prepared by the U.S. and Drug administration.

By “patient” is meant any animal for which treatment is desirable.Patients may be mammals, and typically, as used herein, a patient is ahuman individual.

The term “pharmaceutically acceptable salt,” as used herein, representssalts or zwitterionic forms of the compounds of the present inventionwhich are water or oil-soluble or dispersible; which are suitable fortreatment of diseases without undue toxicity, irritation, andallergic-response; which are commensurate with a reasonable benefit/riskratio; and which are effective for their intended use. The salts can beprepared during the final isolation and purification of the compounds orseparately by reacting the appropriate compound in the form of the freebase with a suitable acid. Representative acid addition salts includeacetate, adipate, alginate, L-ascorbate, aspartate, benzoate,benzenesulfonate (besylate), bisulfate, butyrate, camphorate,camphorsulfonate, citrate, digluconate, formate, fumarate, gentisate,glutarate, glycerophosphate, glycolate, hemisulfate, heptanoate,hexanoate, hippurate, hydrochloride, hydrobromide, hydroiodide,2-hydroxyethansulfonate (isethionate), lactate, maleate, malonate,DL-mandelate, mesitylenesulfonate, methanesulfonate,naphthylenesulfonate, nicotinate, 2-naphthalenesulfonate, oxalate,pamoate, pectinate, persulfate, 3-phenylproprionate, phosphonate,picrate, pivalate, propionate, pyroglutamate, succinate, sulfonate,tartrate, L-tartrate, trichloroacetate, trifluoroacetate, phosphate,glutamate, bicarbonate, para-toluenesulfonate (p-tosylate), andundecanoate. Also, basic groups in the compounds of the presentinvention can be quaternized with methyl, ethyl, propyl, and butylchlorides, bromides, and iodides; dimethyl, diethyl, dibutyl, and diamylsulfates; decyl, lauryl, myristyl, and steryl chlorides, bromides, andiodides; and benzyl and phenethyl bromides. Examples of acids which canbe employed to form pharmaceutically acceptable addition salts includeinorganic acids such as hydrochloric, hydrobromic, sulfuric, andphosphoric, and organic acids such as oxalic, malcic, succinic, andcitric. Salts can also be formed by coordination of the compounds withan alkali metal or alkaline earth ion.

Hence, the present invention contemplates sodium, potassium, magnesium,and calcium salts of the compounds of the compounds of the presentinvention and the like.

The term “solvates” is used in its broadest sense. For example, the termsolvates includes hydrates formed when a compound of the presentinvention contains one or more bound water molecules.

The term “alkyl,” as used herein, alone or in combination, refers to astraight-chain or branched-chain alkyl radical containing from 1 to andincluding 20, preferably 1 to 10, and more preferably 1 to 6, carbonatoms. The term “alkyl groups” is used in its broadest sense. Alkylgroups may be optionally substituted as defined herein. Examples ofalkyl radicals include methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, sec-butyl, tert-butyl, pentyl, iso-amyl, hexyl, octyl, noyland the like. For example, the O(C₁-C₈)-alkyl groups comprises thestraight O(C₁-C₈)-alkyl groups as well as the branched O(C₁-C₈)-alkylgroups. For another example, the term comprises cycloalkyl groups, asfor example, the (C₁-C₈)-alkyl groups comprises the (C₃-C₈)-cycloalkylgroups.

The term “alkenyl” is used in its broadest sense. For example, the termalkenyl refers to branched, unbranched, and cyclic unsaturatedhydrocarbon chains comprising a designated number of carbon atoms. Forexample, (C₂-C₈) alkenyl embraces straight, branched, and cyclichydrocarbon chains containing 2 to 8 carbon atoms having at least onedouble bond, and the term includes but is not limited to substituentssuch as ethenyl, propenyl, iso-propenyl, butenyl, iso-butenyl,sec-butenyl, tert-butenyl, n-pentenyl, n-hexenyl, and the like, unlessotherwise indicated.

The term “alkynyl” is used in its broadest sense. For example, the termalkynyl refers to branched, unbranched, and cyclic unsaturatedhydrocarbon chains comprising a designated number of carbon atoms. Forexample, (C₂-C₈) alkynyl embraces straight, branched, and cyclichydrocarbon chains containing 2 to 8 carbon atoms having at least onetriple bond, and the term includes but is not limited to substituentssuch as ethynyl, propynyl, butenyl, n-pentynyl and branchedcounterparts, n-hexynyl and branched counterparts, and the like, unlessotherwise indicated.

The term “cycloalkyl,” as used herein, alone or in combination, refersto a saturated or partially saturated monocyclic, bicyclic or tricyclicalkyl radical wherein each cyclic moiety contains from 3 to 12,preferably three to seven, carbon atom ring members and which mayoptionally be a benzo fused ring system which is optionally substitutedas defined herein. Examples of such cycloalkyl radicals includecyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,octahydronaphthyl, 2,3-dihydro-1H-indenyl, adamantyl and the like.“Bicyclic” and “tricyclic” as used herein are intended to include bothfused ring systems, such as decahydonapthalene, octahydronapthalene aswell as the multicyclic (multicentered) saturated or partiallyunsaturated type. The latter type of isomer is exemplified in general bybicyclo[2,2,2]octane, bicyclo[2,2,2]octane, bicyclo[1,1,1]pentane,camphor and bicyclo[3,2,1]octane.

The term “cycloalkenyl,” as used herein, alone or in combination, refersto a partially unsaturated monocyclic, bicyclic or tricyclic radicalwherein each cyclic moiety contains from 3 to 12, preferably five toeight, carbon atom ring members and which may optionally be a benzofused ring system which is optionally substituted as defined herein.Examples of such cycloalkenyl radicals include cyclopentenyl,cyclohexenyl, cyclohexadienyl, cycloheptenyl, cyclooctadienyl,-1H-indenyl and the like.

The term “cycloalkylalkyl,” as used herein, alone or in combination,refers to an alkyl radical as defined above which is substituted by acycloalkyl radical as defined above. Examples of such cycloalkylalkylradicals include cyclopropylmethyl, cyclobutylmethyl, cyclopentylmethyl,cyclohexylmethyl, 1-cyclopentylethyl, 1-cyclohexylethyl,2-cyclopentylethyl, 2-cyclohexylethyl, cyclobutylpropyl,cyclopentylpropyl, cyclohexylbutyl and the like.

The term “cycloalkenylalkyl,” as used herein, alone or in combination,refers to an alkyl radical as defined above which is substituted by acycloalkenyl radical as defined above. Examples of suchcycloalkenylalkyl radicals include 1-methylcyclohex-1-enyl-,4-ethylcyclohex-1-enyl-, 1-butylcyclopent-1-enyl-,3-methylcyclopent-1-enyl- and the like.

The term “ester,” as used herein, alone or in combination, refers to acarbonyloxy —(C═O)O— group bridging two moieties linked at carbon atoms.Examples include ethyl benzoate, n-butyl cinnamate, phenyl acetate andthe like.

The term “acyl,” as used herein, alone or in combination, refers to acarbonyl attached to an alkyl, alkenyl, aryl, heteroaryl, heterocycle,or any other moiety where the atom attached to the carbonyl is carbon.An “acetyl” group refers to a —C(O)CH₃ group. Examples of acyl groupsinclude alkanoyl groups such as formyl, acetyl, and propionyl, aroylgroups such as benzoyl, and mixed alkyl-aryl groups such as cinnamoyl.

The term “alkoxycarbonyl,” as used herein, alone or in combination,refers to an alkoxy group attached to the parent molecular moietythrough a carbonyl group. Examples of such “alkoxycarbonyl” groupsinclude methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyland hexyloxycarbonyl.

The term “alkylamino,” as used herein, alone or in combination, refersto an amino group attached to the parent molecular moiety through analkyl group.

The term “alkanoyl,” as used herein, refers to an alkyl group attachedto the parent molecular moiety through a carbonyl group. Examples ofsuch groups include methylcarbonyl, also known as acetyl; ethylcarbonyl,also known as propionyl; and 2-methyl-cyclopentylcarbonyl, etc.

The term “alkylsulfonyl,” as used herein, alone or in combination,refers to an alkyl group attached to the parent molecular moiety througha sulfonyl group. Examples of alkylsulfinyl groups includemethanesulfonyl, ethanesulfonyl, tert-butanesulfonyl, and the like.

The term “alkylthio,” as used herein, alone or in combination, refers toan alkyl thioether (R-S-) radical wherein the term alkyl is as definedabove. Examples of suitable alkyl thioether radicals include methylthio,ethylthio, n-propylthio, isopropylthio, n-butylthio, iso-butylthio,sec-butylthio, tert-butylthio, ethoxyethylthio, methoxypropoxyethylthio,ethoxypentoxyethoxyethylthio and the like.

The term “alkylthioalkyl” embraces alkylthio radicals attached to analkyl radical. Alkylthioalkyl radicals include “lower alkylthioalkyl”radicals having alkyl radicals of one to six carbon atoms and analkylthio radical as described above. Examples of such radicals includemethylthiomethyl.

The term “amido,” as used herein, alone or in combination, refers to anamino group as described below attached to the parent molecular moietythrough a carbonyl or sulfonyl group. The term “C-amido” as used herein,alone or in combination, refers to a —C(═O)—NR group with R as definedherein. The term “N-amido” as used herein, alone or in combination,refers to a RC(═O)NH— group, with R as defined herein.

The term “amino,” as used herein, alone or in combination, refers to—NRR′, wherein R and R′ are independently selected from the groupconsisting of hydrogen, alkenyl, alkoxy, alkoxyalkyl, alkoxycarbonyl,alkyl, alkylcarbonyl, aryl, arylalkenyl, arylalkyl, cycloalkyl,haloalkylcarbonyl, heteroaryl, heteroarylalkenyl, heteroarylalkyl,heterocycle, heterocycloalkenyl, and heterocycloalkyl, wherein the aryl,the aryl part of the arylalkenyl, the arylalkyl, the heteroaryl, theheteroaryl part of the heteroarylalkenyl and the heteroarylalkyl, theheterocycle, and the heterocycle part of the heterocycloalkenyl and theheterocycloalkyl can be optionally substituted with one, two, three,four, or five substituents independently selected from the groupconsisting of alkenyl, alkoxy, alkoxyalkyl, alkyl, cyano, halo,haloalkoxy, haloalkyl, hydroxy, hydroxy-alkyl, nitro, and oxo.

The term “aminoalkyl,” as used herein, alone or in combination, refersto an amino group attached to the parent molecular moiety through analkyl group. Examples include aminomethyl, aminoethyl and aminobutyl.The term “alkylamino” denotes amino groups which have been substitutedwith one or two alkyl radicals. Suitable “alkylamino” groups may bemono- or dialkylated, forming groups such as, for example,N-methylamino, N-ethylamino, N,N-dimethylamino, N,N-diethylamino and thelike.

The terms “aminocarbonyl” and “carbamoyl,” as used herein, alone or incombination, refer to an amino-substituted carbonyl group, wherein theamino group can be a primary or secondary amino group containingsubstituents selected from alkyl, aryl, aralkyl, cycloalkyl,cycloalkylalkyl radicals and the like.

The term “aryl,” as used herein, alone or in combination, means acarbocyclic aromatic system containing one, two or three rings whereinsuch rings may be attached together in a pendent manner or may be fused.The term “aryl” embraces aromatic radicals such as phenyl, naphthyl,anthracenyl, phenanthryl, and biphenyl. The aryl groups of the presentinvention can be optionally substituted with one, two, three, four, orfive substituents independently selected from the groups as definedherein.

The term “arylalkenyl,” as used herein, refers to an aryl group attachedto the parent molecular moiety through an alkenyl group.

The term “arylalkoxy,” as used herein, refers to an aryl group attachedto the parent molecular moiety through an alkoxy group.

The term “arylamino” as used herein, alone or in combination, refers toan aryl group attached to the parent moiety through an amino group, suchas N-phcnylamino, and the like.

The term “aryloxy,” as used herein, alone or in combination, refers toan aryl group attached to the parent molecular moiety through an oxygenatom.

The term “arylsulfonyl,” as used herein, alone or in combination, refersto an aryl group attached to the parent molecular moiety through asulfonyl group.

The term “arylthio,” as used herein, alone or in combination, refers toan aryl group attached to the parent molecular moiety through a sulfuratom.

The terms “carboxy” or “carboxyl,” whether used alone or with otherterms, such as “carboxyalkyl,” denotes —CO₂H.

The terms “benzo” and “benz,” as used herein, alone or in combination,refer to the divalent radical C₆H₄═ derived from benzene. Examplesinclude benzothiophene and benzimidazole.

The term “carbamoyloxy,” as used herein, alone or in combination, refersto an amino-substituted carbonyl group attached to the parent molecularmoiety through an oxygen atom (e.g. RR′NC(═O)O—), wherein the aminogroup can be a primary or secondary amino group containing substituentsselected from alkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl radicalsand the like.

The term “carbonate” as used herein, alone or in combination, refers toa —O—C(═O)OR group, with R as defined herein.

The term “carbonyl,” as used herein, when alone includes formyl [—C(O)H]and in combination is a —C(O)— group.

The term “carboxy,” as used herein, refers to —C(O)OH or thecorresponding “carboxylate” such as a carboxylic acid salt derivative orester derivative. An “O-carboxy” group refers to a RC(O)O— group, whereR is as defined herein. A “C-carboxy” group refers to a —C(O)OR groupswhere R is as defined herein.

The term “cyano,” as used herein, alone or in combination, refers to—CN.

The term “cycloalkyl,” as used herein, alone or in combination, refersto a saturated or partially saturated monocyclic, bicyclic or tricyclicalkyl radical wherein each cyclic moiety contains from 3 to 12,preferably three to seven, carbon atom ring members and which mayoptionally be a benzo fused ring system which is optionally substitutedas defined herein. Examples of such cycloalkyl radicals includecyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,octahydronaphthyl, 2,3-dihydro-1H-indenyl, adamantyl and the like.“Bicyclic” and “tricyclic” as used herein are intended to include bothfused ring systems, such as decahydonapthalene, octahydronapthalene aswell as the multicyclic (multicentered) saturated or partiallyunsaturated type. The latter type of isomer is exemplified in general bybicyclo[2,2,2]octane, bicyclo[2,2,2]octane, bicyclo[1,1,1]pentane,camphor and bicyclo[3,2,1]octane.

The term “cycloalkenyl,” as used herein, alone or in combination, refersto a partially unsaturated monocyclic, bicyclic or tricyclic radicalwherein each cyclic moiety contains from 3 to 12, preferably five toeight, carbon atom ring members and which may optionally be a benzofused ring system which is optionally substituted as defined herein.Examples of such cycloalkenyl radicals include cyclopentenyl,cyclohexenyl, cyclohexadienyl, cycloheptenyl, cyclooctadienyl,-1H-indenyl and the like.

The term “cycloalkylalkyl,” as used herein, alone or in combination,refers to an alkyl radical as defined above which is substituted by acycloalkyl radical as defined above. Examples of such cycloalkylalkylradicals include cyclopropylmethyl, cyclobutylmethyl, cyclopentylmethyl,cyclohexylmethyl, 1-cyclopentylethyl, 1-cyclohexylethyl,2-cyclopentylethyl, 2-cyclohexylethyl, cyclobutylpropyl,cyclopentylpropyl, cyclohexylbutyl and the like.

The term “cycloalkenylalkyl,” as used herein, alone or in combination,refers to an alkyl radical as defined above which is substituted by acycloalkenyl radical as defined above. Examples of suchcycloalkenylalkyl radicals include 1-methylcyclohex-1-enyl-,4-ethylcyclohex-1-enyl-, 1-butylcyclopent-1-enyl-,3-methylcyclopent-1-enyl- and the like.

The term “ester,” as used herein, alone or in combination, refers to acarbonyloxy —(C═O)O— group bridging two moieties linked at carbon atoms.Examples include ethyl benzoate, n-butyl cinnamate, phenyl acetate andthe like.

The term “ether,” as used herein, alone or in combination, refers to anoxy group bridging two moieties linked at carbon atoms.

The term “halo,” or “halogen,” as used herein, alone or in combination,refers to fluorine, chlorine, bromine, or iodine.

The term “haloalkoxy,” as used herein, alone or in combination, refersto a haloalkyl group attached to the parent molecular moiety through anoxygen atom.

The term “haloalkyl,” as used herein, alone or in combination, refers toan alkyl radical having the meaning as defined above wherein one or morehydrogens are replaced with a halogen. Specifically embraced aremonohaloalkyl, dihaloalkyl and polyhaloalkyl radicals. A monohaloalkylradical, for one example, may have an iodo, bromo, chloro or fluoro atomwithin the radical. Dihalo and polyhaloalkyl radicals may have two ormore of the same halo atoms or a combination of different halo radicals.Examples of haloalkyl radicals include fluoromethyl, difluoromethyl,trifluoromethyl, chloromethyl, dichloromethyl, trichloromethyl,trichloroethyl, pentafluoroethyl, heptafluoropropyl,difluorochloromethyl, dichlorofluoromethyl, difluoroethyl,difluoropropyl, dichloroethyl and dichloropropyl. “Haloalkylene” refersto a halohydrocarbyl group attached at two or more positions. Examplesinclude fluoromethylene (—CFH—), difluoromethylene (—CF₂—),chloromethylene (—CHCl—) and the like. Examples of such haloalkylradicals include chloromethyl, 1-bromoethyl, fluoromethyl,difluoromethyl, trifluoromethyl, 1,1,1-trifluoroethyl, perfluorodccyland the like.

The term “heteroalkyl,” as used herein, alone or in combination, refersto a stable straight or branched chain, or cyclic hydrocarbon radical,or combinations thereof, fully saturated or containing from 1 to 3degrees of unsaturation, consisting of the stated number of carbon atomsand from one to three heteroatoms selected from the group consisting ofO, N, and S, and wherein the nitrogen and sulfur atoms may optionally beoxidized and the nitrogen heteroatom may optionally be quaternized. Theheteroatom(s) O, N and S may be placed at any interior position of theheteroalkyl group. Up to two heteroatoms may be consecutive, such as,for example, —CH₂—NH—OCH₃.

The term “heteroaryl,” as used herein, alone or in combination, refersto an aromatic five- or six-membered ring, where at least one atom isselected from the group consisting of N, O, and S, and the remainingring atoms are carbon. The five-membered rings have two double bonds,and the six-membered rings have three double bonds. The heteroarylgroups are connected to the parent molecular group through asubstitutable carbon or nitrogen atom in the ring. The term “heteroaryl”also includes systems where a heteroaryl ring is fused to an aryl group,as defined herein, a heterocycle group, as defined herein, or anadditional heteroaryl group. Heteroaryls are exemplified bybenzothienyl, benzoxazolyl, benzofuranyl, benzimidazolyl, benzthiazolylbenzotriazolyl, cinnolinyl, furyl, imidazolyl, triazolyl [e.g.,4H-1,2,4-triazolyl, 1H-1,2,3-triazolyl, 2H-1,2,3-triazolyl, etc.],tetrazolyl [e.g. 1H-tetrazolyl, 2H-tetrazolyl, etc.], indazolyl,indolyl, isoxazolyl, isoquinolinyl, isothiazolyl, naphthyridinyl,oxadiazolyl [e.g., 1,2,4-oxadiazolyl, 1,3,4-oxadiazolyl,1,2,5-oxadiazolyl, etc.], oxazolyl, isoxazolyl, purinyl, thiazolyl,isothiazolyl, thienopyridinyl, thienyl, thiadiazolyl [e.g.,1,2,4-thiadiazolyl, 1,3,4-thiadiazolyl, 1,2,5-thiadiazolyl, etc.],pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, pyrazolyl, pyrrolyl,pyrido[2,3-d]pyrimidinyl, pyrrolo[2,3-b]pyridinyl, quinazolinyl,quinolinyl, thieno[2,3-c]pyridinyl, tetrazolyl, triazinyl, and the like.The heteroaryl groups of the present invention can be optionallysubstituted with one, two, three, four, or five substituentsindependently selected from the groups as defined herein.

Examples of heteroaryl groups include, without limitation, thienyl,benzothienyl, furyl, benzofuryl, dibenzofuryl, pyrrolyl, imidazolyl,pyrazolyl, pyridyl, pyrazinyl, pyrimidinyl, indolyl, quinolyl,isoquinolyl, quinoxalinyl, tetrazolyl, oxazolyl, thiazolyl, triazolyl,and isoxazolyl

The term “heteroaralkyl” or “heteroarylalkyl,” as used herein, alone orin combination, refers to a heteroaryl group attached to the parentmolecular moiety through an alkyl group.

The term “heteroaralkenyl” or “heteroarylalkenyl,” as used herein, aloneor in combination, refers to a heteroaryl group attached to the parentmolecular moiety through an alkenyl group.

The term “heteroaralkoxy” or “heteroarylalkoxy,” as used herein, aloneor in combination, refers to a heteroaryl group attached to the parentmolecular moiety through an alkoxy group.

The term “heteroaralkylidene” or “heteroarylalkylidene,” as used herein,alone or in combination, refers to a heteroaryl group attached to theparent molecular moiety through an alkylidene group.

The term “heteroaryloxy,” as used herein, alone or in combination,refers to a heteroaryl group attached to the parent molecular moietythrough an oxygen atom.

The term “heteroarylsulfonyl,” as used herein, alone or in combination,refers to a heteroaryl group attached to the parent molecular moietythrough a sulfonyl group.

The terms “heterocycloalkyl” and, interchangeably, “heterocycle,” asused herein, alone or in combination, each refer to a saturated,partially unsaturated, or fully unsaturated monocyclic, bicyclic, ortricyclic heterocyclic radical containing one or more heteroatoms asring members, wherein each said heteroatom may be independently selectedfrom the group consisting of nitrogen, oxygen, and sulfur, and whereinthere are typically 3 to 8 ring members in each ring. Most commonlyheterocyclic rings contain 5 to 6 ring members. In some embodiments ofthis invention heterocyclic rings contain 1 to 4 heteroatoms; in otherembodiments, heterocyclic rings contain 1 to 2 heteroatoms.“Heterocycloalkyl” and “heterocycle” are intended to include sulfones,sulfoxides, N-oxides of tertiary nitrogen ring members, and carbocyclicfused and benzo fused ring systems; additionally, both terms alsoinclude systems where a heterocycle ring is fused to an aryl group, asdefined herein, or an additional heterocycle group. Heterocycle groupsof the invention are exemplified by aziridinyl, azetidinyl,1,3-benzodioxolyl, dihydroisoindolyl, dihydroisoquinolinyl,dihydrocinnolinyl, dihydrobenzodioxinyl,dihydro[1,3]oxazolo[4,5-b]pyridinyl, benzothiazolyl, dihydroindolyl,dihy-dropyridinyl, 1,3-dioxanyl, 1,4-dioxanyl, 1,3-dioxolanyl,isoindolinyl, morpholinyl, piperazinyl, pyrrolidinyl,tetrahydropyridinyl, piperidinyl, thiomorpholinyl, and the like. Theheterocycle groups may be optionally substituted unless specificallyprohibited.

The term “heterocycloalkenyl,” as used herein, alone or in combination,refers to a heterocycle group attached to the parent molecular moietythrough an alkenyl group.

The term “heterocycloalkoxy,” as used herein, alone or in combination,refers to a heterocycle group attached to the parent molecular groupthrough an oxygen atom.

The term “hctcrocycloalkylalkyl,” as used herein, alone or incombination, refers to an alkyl radical as defined above in which atleast one hydrogen atom is replaced by a heterocycloalkyl radical asdefined above, such as pyrrolidinylmethyl, tetrahydrothienylmethyl,pyridylmethyl and the like.

The term “heterocycloalkylidene,” as used herein, alone or incombination, refers to a heterocycle group attached to the parentmolecular moiety through an alkylidene group.

The term “hydrazinyl” as used herein, alone or in combination, refers totwo amino groups joined by a single bond, i.e., —N—N—.

The term “hydroxy,” as used herein, alone or in combination, refers to—OH.

The term “hydroxyalkyl” as used herein, alone or in combination, refersto a linear or branched alkyl group having one to about ten carbon atomsany one of which may be substituted with one or more hydroxyl radicals.Examples of such radicals include hydroxymethyl, hydroxyethyl,hydroxypropyl, hydroxybutyl and hydroxyhexyl.

The term “hydroxyalkyl,” as used herein, alone or in combination, refersto a hydroxy group attached to the parent molecular moiety through analkyl group.

The term “lower,” as used herein in such terms as “lower alkyl,” aloneor in combination, means containing from 1 to and including 6 carbonatoms.

The term “optionally substituted” means the anteceding group may besubstituted or unsubstituted. When substituted, the hydrogen atoms boundto the carbon, nitrogen, sulfur, or oxygen atoms are replaced by“substituents” which may include carbonyl (oxo), carboxyl, lower alkylcarboxylate, lower alkyl carbonate, lower alkyl carbamate, halogen,hydroxy, amino, amido, cyano, hydrazinyl, hydrazinylcarbonyl,alkylhydrazinyl, dialkylhydrazinyl, aiylhydrazinyl,heteroarylhydrazinyl, nitro, thiol, sulfonic acid, trisubstituted silyl,urea, acyl, acyloxy, acylamino, acylthio, lower alkyl, lower alkylamino,lower dialkylamino, lower alkyloxy, lower alkoxyalkyl, lower alkylthio,lower alkylsulfonyl, lower alkenyl, lower alkenylamino, lowerdialkenylamino, lower alkenyloxy, lower alkenylthio, lower alkenylsulfonyl, lower alkynyl, lower alkynylamino, lower dialkynylamino, loweralkynyloxy, lower alkynylthio, lower alkynylsulfonyl, lower cycloalkyl,lower cycloalkyloxy, lower cycloalkylamino, lower cycloalkylthio, lowercycloalkylsulfonyl, lower cycloalkylalkyl, lower cycloalkylalkyloxy,lower cycloalkylalkylamino, lower cycloalkylalkylthio, lowercycloalkylalkylsulfonyl, aryl, aryloxy, arylamino, arylthio,arylsulfonyl, arylalkyl, arylalkyloxy, arylalkylamino, arylalkylthio,arylalkylsulfonyl, heteroaryl, heteroaryloxy, heteroarylamino,heteroarylthio, heteroarylsulfonyl, heteroarylalkyl, heteroarylalkyloxy,heteroarylalkylamino, heteroarylalkylthio, heteroarylalkylsulfonyl,heterocycloalkyl, heterocycloalkyloxy, heterocycloalkylamino,heterocycloalkylthio, heterocycloalkylsulfonyl, lower haloalkyl, lowerhaloalkenyl, lower haloalkynyl, lower perhaloalkyl, lower perhaloalkoxy,lower haloalkoxy, and lower acyloxy. Two substituents may be joinedtogether to form a fused four-, five-, six-, or seven-memberedcarbocyclic or heterocyclic ring consisting of zero to threeheteroatoms, for example forming methylenedioxy or ethylenedioxy. Anoptionally substituted group may be unsubstituted (e.g., —CH₂CH₃), fullysubstituted (e.g., —CF₂CF₃), monosubstituted (e.g., —CH₂CH₂F) orsubstituted at a level anywhere in-between fully substituted andmonosubstituted (e.g., —CH₂CF₃). Where substituents are recited withoutqualification as to substitution, both substituted and unsubstitutedforms are encompassed. Where a substituent is qualified as“substituted,” the substituted form is specifically intended. Allpendant aryl, heteroaryl, and heterocyclo moieties can be furtheroptionally substituted with one, two, three, four, or five substituentsindependently selected from the groups listed above.

The terms “oxy” or “oxa,” as used herein, alone or in combination, referto —O—.

The term “oxo” as used herein, alone or in combination, refers to adoubly bonded oxygen ═O.

The term “perhaloalkoxy” refers to an alkoxy group where all of thehydrogen atoms are replaced by halogen atoms.

The term “perhaloalkyl” as used herein, alone or in combination, refersto an alkyl group where all of the hydrogen atoms are replaced byhalogen atoms.

The term “phosphonate” as used herein, alone or in combination, refersto the —P(═O)(OG)(OG1) group, where G and G1 are chosen from H, alkyl,alkenyl, alkynyl, aryl, heteroaryl, etc.

The term “phosphinate” as used herein, alone or in combination, refersto the —P(═O)(G)(OG1) group, where G and G1 are chosen from H, alkyl,alkenyl, alkynyl, aryl, heteroaryl, etc.

The terms “sulfonate,” “sulfonic acid,” and “sulfonic,” as used herein,alone or in combination, refers the —SO₃H group and its anion as thesulfonic acid is used in salt formation.

The term “sulfanyl,” as used herein, alone or in combination, refers to—S and —S—.

The term “sulfinyl,” as used herein, alone or in combination, refers to—S(O)—.

The term “sulfonyl,” as used herein, alone or in combination, refers to—SO₂—.

The term “N-sulfonamido” refers to a RS(═O)₂NH— group with R as definedherein.

The term “S-sulfonamido” refers to a —S(═O)₂NR₂, group, with R asdefined herein.

The terms “thia” and “thio,” as used herein, alone or in combination,refer to a —S— group or an ether wherein the oxygen is replaced withsulfur. The oxidized derivatives of the thio group, namely sulfinyl andsulfonyl, are included in the definition of thia and thio.

Prodrug Moiety

The compounds of the present embodiments are prodrugs of tizoxanide, ananalogue or salt thereof, for example, analogues disclosed in U.S. Pat.Nos. 7,645,783, 7,550,493, 7,285,567, 6,117,894, 6,020,353, 5,968,961,5,965,590, 5,935,591, and 5,886,013 and U.S. application Ser. Nos.12/184,760, 12/656,704, 12/821,571, 12/777,383, 13/284,242, 13/471,948.In one embodiment, the tizoxanide, an analogue or salt thereof containsat least one hydroxy moiety on the phenyl ring. The correspondingprodrug contains an ester moiety comprising the amino acid moiety. Inone embodiment, the tizoxanide analogue is identical to tizoxanide,except that the nitro group is replaced by Cl.

Amino acids used in the prodrugs of the present disclosure can by anynatural or unnatural amino acid. For example, in one embodiment, theamino acid is selected from the group consisting of alanine, arginine,asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine,histidine, isoleucine, leucine, lysine, methionine, phenylalanine,proline, serine, threonine, tryptophan, tyrosine, and valine. In oneembodiment, the amino acid comprises a hydrophobic side chain, forexample, alanine, isoleucine, leucine, methionine, phenylalanine,tryptophan, tyrosine, and valine. In one embodiment, the amino acidcomprises an alkyl side chain, for example, alanine, isoleucine,leucine, and valine.

In another embodiment, the amino acid bound to tizoxanide, an analogueor salt thereof is represented by the following formula (A):

wherein R′ is selected from the group consisting of hydrogen, alkyl, anda nitrogen protecting group;

R″ is selected from the group consisting of alkyl, alkenyl, alkynyl,cycloalkyl, cycloalkylalkyl, cycloalkylalkenyl, cycloalkylalkynyl,cycloalkenyl, cycloalkenylalkyl, cycloalkenylalkenyl,cycloalkenylalkynyl.

In one embodiment, R′ is selected from the group consisting of hydrogenand a nitrogen protecting group, and R″ is a straight-chain,branched-chain, or cyclic unsaturated (C₁-C₁₀)-alkyl moiety. In anotherembodiment, R″ is a straight-chain or branched-chain (C₁-C₅)-alkylmoiety or R″ is a (C₁-C₃)-alkyl moiety or R″ is a C₃-alkyl moiety. Insome embodiments, R′ is hydrogen.

The amino acid moiety may be racemic or may be optically active. In someembodiments, the amino acid moiety has an enantiomeric excess of atleast 50, 60, 70, 80, 90, 95, 96, 97, 98, 99, 99.5, 99.9% or greater. Inone embodiment, wherein Formula A is a moiety selected from

wherein R′ and R″ can be any of the previously defined values.

In other embodiments, the amino acid bound to tizoxanide, an analogue orsalt thereof is represented by the following formula (A′):

wherein R′ is selected from the group consisting of hydrogen, alkyl, anda nitrogen protecting group;

R″ is selected from the group consisting of alkyl, alkenyl, alkynyl,cycloalkyl, cycloalkylalkyl, cycloalkylalkenyl, cycloalkylalkynyl,cycloalkenyl, cycloalkenylalkyl, cycloalkenylalkenyl,cycloalkenylalkynyl, and

wherein R″ is substituted by one or more selected from the group of OH,NH₂, SeH, SH or CONH₂, or a protected OH, NH₂, SeH, SH or CONH₂.

In other embodiments, the amino acid bound to tizoxanide, an analogue orsalt thereof is represented by the following formula (B):

wherein R′ is selected from the group consisting of hydrogen, alkyl, anda nitrogen protecting group;

R″ and are independently selected from the group consisting of alkyl,alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, cycloalkylalkenyl,cycloalkylalkynyl, cycloalkenyl, cycloalkenylalkyl, cycloalkenylalkenyl,cycloalkenylalkynyl, and

wherein R″ is optionally substituted by one or more selected from thegroup of OH, NH₂, SeH, SH or CONH₂, or a protected OH, NH₂, SeH, SH orCONH₂.

Protecting groups for OH, NH₂, ScH, SH or CONH₂ are known in the art,and are disclosed, for example, in Wuts, P G M Greene's ProtectiveGroups in Organic Synthesis 4th edn (John Wiley & Sons, New York, 2007,which is incorporated by reference in its entirety.

Active Moiety

The active moiety of the present embodiments is prodrugs of tizoxanideor analogue or salts thereof. Examples of analogues within the scope ofthe disclosure are those listed in analogues disclosed in U.S. Pat. Nos.7,645,783, 7,550,493, 7,285,567, 6,117,894, 6,020,353, 5,968,961,5,965,590, 5,935,591, and 5,886,013 and U.S. application Ser. Nos.12/184,760, 12/656,704, 12/821,571, 12/777,383, 13/284,242, 13/471,948.In one embodiment, the analogue is a compound of Formula (I)

wherein R₁ through R₅ are, independently, selected from the groupconsisting of hydrogen, CN, NO₂, F, Cl, Br, I, hydroxy, alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkylalkyl, cycloalkylalkenyl,cycloalkylalkynyl, cycloalkenyl, cycloalkenylalkyl, cycloalkenylalkenyl,cycloalkenylalkynyl, alkoxy, alkenyloxy, alkynyloxy, alkoxyalkyl,alkoxyalkenyl, alkoxyalkynyl, alkenyloxyalkyl, alkenyloxyalkenyl,alkenyloxyalkynyl, alkynyloxyalkyl, alkenyloxyalkenyl,alkenyloxyalkynyl, cycloalkoxy, cycloalkylalkoxy, cycloalkylalkenyloxy,cycloalkylalkynyloxy, cycloalkenyloxy, cycloalkenylalkoxy,cycloalkenylalkenyloxy, cycloalkenylalkynyloxy, alkoxyalkylamino,hydroxyalkyl, acyl, acyloxy, aroyloxy, arylalkanoyloxy, arylalkenoyloxy,heteroaroyloxy, heteroarylalkanoyloxy, heteroarylalkenoyloxy,alkoxycarbonyl, aryloxycarbonyl, arylalkoxycarbonyl,heteroaryloxycarbonyl, heteroarylalkoxycarbonyl, alkoxycarbonyloxy,carbamoyl, carbamoyloxy, alkylamino, dialkylamino, alkylaminoalkyl,amido, alkylamido, dialkylamido, haloalkyl, perhaloalkyl, perhaloalkoxy,alkylthio, alkylthioalkyl, alkylsulfonyl, alkylsulfonylalkyl,alkenylsulfonyl, alkynylsulfonyl, cycloalkylsulfonyl,cycloalkylalkylsulfonyl, cycloalkylsulfonylalkyl,cycloalkylalkylsulfonylalkyl, arylsulfonyl, arylalkylsulfonyl,arylalkenylsulfonyl, heteroarylsulfonyl, heteroarylalkylsulfonyl,heteroarylalkenylsulfonyl, alkylsulfonamido, N,N′-dialkylsulfonamido,sulfonamidoalkyl, sulfonamidoaryl, sulfonamidoarylalkyl,sulfonamidoarylalkenyl, aryl, arylalkyl, aryloxy, arylalkoxy, arylthio,arylalkylthio, arylamino, arylalkylamino, arylalkenyl, arylalkynyl,heteroaryl, heteroarylalkyl, heteroarylalkenyl, heteroarylalkynyl,heteroaryloxy, heteroarylalkoxy, heteroarylamino, heteroarylalkylamino,heteroarylthio, heteroarylalkylthio, heteroarylalkylamino,heterocycloalkyl, heterocycloalkenyl, heterocycloalkoxy, andheterocycloalkenyloxy, any of which may be optionally substituted,

and where each of R₁ through R₅ comprises 1 to 60 atoms;

provided at least one of R₁ through R₅ is an amino acid moiety bound tothe phenyl through an ester moiety, or a pharmaceutically acceptablesalt thereof.

In one embodiment, R₆ is selected from the group consisting of NO₂, F,Cl, Br, —SO₂—(C₁-C₁₀)-alkyl, —SO—(C₁-C₁₀)-alkyl, haloalkyl,perhaloalkyl, haloalkoxy, perhaloalkoxy, S(O)_(m)C(R₇R₈)_(n)CF₃, andC(R₇R₈)_(n)CF₃, and R₉ is hydrogen, or wherein R₉ is selected from thegroup consisting of NO₂, F, Cl, Br, —SO₂—(C₁-C₁₀)-alkyl,—SO—(C₁-C₁₀)-alkyl, haloalkyl, perhaloalkyl, haloalkoxy, perhaloalkoxy,S(O)_(m)C(R₇R₈)_(n)CF₃, and C(R₇R₈)_(n)CF₃, and R₆ is hydrogen. Inanother embodiment, R₆ is selected from the group consisting of NO₂, F,Cl, Br, —SO₂—(C₁-C₁₀)-alkyl, and —SO—(C₁-C₁₀)-alkyl, and R₉ is hydrogen,or wherein R₉ is selected from the group consisting of NO₂, F, Cl, Br,—SO₂—(C₁-C₁₀)-alkyl, and —SO—(C₁-C₁₀)-alkyl, and R₆ is hydrogen. In yetanother embodiment, R6 is selected from the group consisting of NO2 andCl, and R9 is hydrogen, or wherein R9 is selected from the groupconsisting of NO2 and Cl, and R6 is hydrogen.

In a particular embodiment, R₉ is hydrogen. In another particularembodiment, R₆ is hydrogen.

In one embodiment, the compound is a compound of formula I, wherein oneof R₁, R₂, and R3 is an amino acid moiety bound to the phenyl through anester moiety R₄, R₅, and the remainder of R₁, R₂, and R₃, are H; and R₆is NO₂ and R₉ is H.

In one embodiment, the compound is a compound of formula I, wherein R₆is NO₂ and R₉ is H. In another embodiment, the compound is a compound offormula I, wherein R₆ is a halo, for example Cl or F and R₉ is H.

In one embodiment, the compound is selected from:

Other compounds listed in U.S. Pat. Nos. 7,645,783, 7,550,493,7,285,567, 6,117,894, 6,020,353, 5,968,961, 5,965,590, 5,935,591, and5,886,013 and U.S. application Ser. Nos. 12/184,760, 12/656,704,12/821,571, 12/777,383, 13/284,242, 13/471,948 that contain at least onehydroxy moiety on a phenyl ring are incorporated in to this disclosureby reference and said compounds with an amino acid moiety bound to thephenyl through an ester moiety at the hydroxy moiety on the phenyl ringare compounds of this disclosure.

Pharmaceutical Compositions

The compounds of the present disclosure are capable of beingincorporated into a pharmaceutical composition comprising the compoundand at least one pharmaceutically acceptable excipient. In oneembodiment, the pharmaceutical composition comprises a prodrug oftizoxanide or analogue of the present disclosure, or pharmaceuticallyacceptable salt thereof, and a pharmaceutically acceptable excipient. Inone embodiment, the pharmaceutical composition is in the form of a solidoral dosage form, such as a tablet or capsule. In another embodiment,the pharmaceutical composition is in the form of a dosage form suitablefor injection, such as intravenous administration.

The pharmaceutical composition may be in the form of an oralpharmaceutical that is immediate release or controlled release. Thepharmaceutical composition may also comprise a compound of the presentdisclosure in addition to another pharmaceutical compound, e.g.,nitazoxanide, tizoxanide or a compound listed in U.S. Pat. Nos.7,645,783, 7,550,493, 7,285,567, 6,117,894, 6,020,353, 5,968,961,5,965,590, 5,935,591, and 5,886,013 and U.S. application Ser. Nos.12/184,760, 12/656,704, 12/821,571, 12/777,383, 13/284,242, 13/471,948.

The pharmaceutical composition comprises an effective amount of acompound of the present disclosure. For example, in one embodiment, thepharmaceutical composition comprises 50 to 600 mg, or 300 to 600 mg or50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300, 350, 400, 450, 500,550, or 600 mg of a compound of the present disclosure. This weight isof the prodrug itself, or based on the weight of the active moiety.

The compositions can contain one or more additional pharmaceuticallyacceptable additives or excipients. In those embodiments with controlledrelease and immediate release portions, both the controlled releaseportion and the immediate release portion can contain one or moreadditional pharmaceutically acceptable additives or excipients. Theseexcipients are therapeutically inert ingredients that are well known andappreciated in the art. As used herein, the term “inert ingredient”refers to those therapeutically inert ingredients that are well known inthe art of pharmaceutical science, which can be used singly or invarious combinations, and include, for example, diluents, disintegrants,binders, suspending agents, glidants, lubricants, fillers, coatingagents, solubilizing agent, sweetening agents, coloring agents,flavoring agents, and antioxidants. See, for example, Remington: TheScience and Practice of Pharmacy 1995, edited by E. W. Martin, MackPublishing Company, 19th edition, Easton, Pa.

Examples diluents or fillers include, but are not limited to, starch,lactose, xylitol, sorbitol, confectioner's sugar, compressible sugar,dextrates, dextrin, dextrose, fructose, lactitol, mannitol, sucrose,talc, microcrystalline cellulose, calcium carbonate, calcium phosphatedibasic or tribasic, dicalcium phosphate dehydrate, calcium sulfate, andthe like.

Diluent(s) or filler(s) typically represent about 2% to about 15% byweight of the entire composition.

Examples of disintegrants include, but are not limited to, alginic acid,methacrylic acid DVB, cross-linked PVP, microcrystalline cellulose,sodium croscarmellose, crospovidone, polacrilin potassium, sodium starchglycolate, starch, including corn or maize starch, pregelatinized starchand the like.

Disintegrant(s) typically represent about 2% to about 15% by weight ofthe entire composition.

Examples of binders include, but are not limited to, starches such aspotato starch, wheat starch, corn starch; microcrystalline cellulose;celluloses such as hydroxypropyl cellulose, hydroxyethyl cellulose,hydroxypropylmethyl cellulose (HPMC), ethyl cellulose, sodium carboxymethyl cellulose; natural gums like acacia, alginic acid, guar gum;liquid glucose, dextrin, povidone, syrup, polyethylene oxide, polyvinylpyrrolidone, poly-N-vinyl amide, polyethylene glycol, gelatin, polypropylene glycol, tragacanth, and the like.

Binder(s) typically represent about 0.2% to about 14% by weight of theentire composition.

Examples of glidants include, but are not limited to, silicon dioxide,colloidal anhydrous silica, magnesium trisilicate, tribasic calciumphosphate, calcium silicate, magnesium silicate, colloidal silicondioxide, powdered cellulose, starch, talc, and the like.

Glidant(s) typically represent about 0.01% to about 0.3% by weight ofthe entire composition.

Examples of lubricants include, but are not limited to, magnesiumstearate, aluminum stearate, calcium stearate, zinc stearate, stearicacid, polyethylene glycol, glyceryl behenate, mineral oil, sodiumstearyl fumarate, talc, hydrogenated vegetable oil and the like.

Lubricant(s) typically represent about 0.2% to about 1.0% by weight ofthe entire composition.

The present compositions can further comprise a coating material. Thecoating material is typically present as an outer layer on the dosageform that completely covers the formulation. For example, in someembodiments, the dosage form is an oral tablet in which the controlledrelease portion forms a first layer of the tablet and the immediaterelease portion forms a second layer that is deposited on top of thefirst layer to form a core tablet. In such embodiments, e.g., thecoating material can be in the form of an outer coating layer that isdeposited on top of the core tablet.

The coating material typically is about 1% to about 5% by weight of thecomposition.

The coating material can comprise hydroxypropylmethylcellulose and/orpolyethylene glycol, and can comprise one or more excipients selectedfrom the group comprising coating agents, opacifiers, taste-maskingagents, fillers, polishing agents, coloring agents, antitacking agentsand the like. For example, the coating material can contain titaniumdioxide as an opacifying agent. Examples of film-coating substances andmethods for using such coating substances are well known to those ofskill in the art.

In one embodiment, the coating is not an enteric coating. In anotherembodiment, the coating is an enteric coating.

For example, the coating material used in the present compositions canbe OPADRY AMB 80W91416 or OPADRY FX 63F97546, as in the examples below.

The controlled release composition may deliver the compound viapH-dependent release, via microbially-triggered delivery, as aconjugate, via time-controlled delivery, via osmotically-regulateddelivery, administered via pressure-controlled delivery, via multimatrix systems delivery, via bioadhesion delivery, or viamultiparticulate delivery. The compound in the controlled releaseformulation may be released preferentially in the small or largeintestine, colon or rectum, in the stomach, esophagus, for example. Insome embodiments, at least 60%, 70%, 80%, or 90% of the administereddose of the compound is released in at least one of the recited regionsof the body over a period of 2-24 hours, or 2, 3, 4, 5, 6, 7, 8, 9, 10,11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 or 24 hours.

Methods of making solid pharmaceutical formulations are known to thoseof skill in the art of pharmaceutical formulations and can be employedto prepare the present compositions. See, for example, Remington: TheScience and Practice of Pharmacy (1995), edited by E. W. Martin, MackPublishing Company, 19th edition, Easton, Pa.

One or more additional active agents may be included in the presentpharmaceutical compositions and methods of treatment. For example, insome embodiments, the compositions may include one or more additionaltherapeutic agents useful in treating hepatitis C such as ribavirin, andimmune-stimulating agents including, but not limited to, interferonssuch as interferon α-2b, a derivative of interferon α-2b such as apolyethylene glycol-conjugated form of interferon α-2b, interferon α-2a,or interferon alfacon-1.

Methods of Treatment

The present compositions can be used to effectively treat anintracellular bacterial infection, a viral infection or a cancer andprovide increased bioavailability and better absorption of nitazoxanide,with fewer of the side effects commonly seen in standard nitazoxanideformulations. In some embodiments, the present compositions display amarked improvement in aqueous solubility, for example, the aqueoussolubility of RM-5061 is 1 mg/mL (“very slightly soluble” to “slightlysoluble”) compared to <0.1 mg/ml (“practically insoluble”) fornitazoxanide, thereby allowing for preparation of injectable, e.g.,intravenous, formulations.

Treatment of intracellular bacterial infections with nitazoxanide isknown in the art. The present methods provide for the treatment of asubject suffering from an intracellular bacterial infection comprisingadministering to the subject in need thereof a therapeutically effectiveamount of a compound or composition of the present disclosure. In oneembodiment, the pharmaceutical composition is administered in an amountof 300 to 600 mg or 300, 350, 400, 450, 500, 550, or 600 mg of acompound of the present disclosure once a day or twice a day or threetimes a day. Treatment regimens may be adjusted based on the knowledgeof one of ordinary skill. For example, the treatment regimen may becarried out over 1, 2, 3, 4, 5, 6, 7 days or 1, 2, 3, or 4 weeks. In oneembodiment, the treatment of a subject suffering from an intracellularbacterial infection comprising administering to the subject in needthereof a therapeutically effective amount of a compound or compositionof the present disclosure provides increased bioavailability or betterabsorption or with of the side effects than a comparative treatment withnitazoxanide.

In another particular aspect of the invention, the subject suffers froman intracellular protozoan infection. In a different particular aspectof the invention, the subject is at risk of developing an intracellularprotozoan infection. In one embodiment, the intracellular protozoaninfection is Cryptosporidium spp. In a different aspect of theinvention, the intracellular protozoan infection is Leishmania spp. Inyet another aspect of the invention, the intracellular protozoaninfection is Toxoplasma gondii. In a further aspect of the invention,the intracellular protozoan infection is Trypanosoma cruzii. In oneparticular embodiment, the prodrug compound of the present disclosure isadministered alone.

In another particular embodiment of the invention, the prodrug compoundof the present disclosure is administered in combination with a vaccine,or an immunostimulant, or an antiprotozoal drug. The antiprotozoal drugmay include, but is not limited to, trimethoprimisulfamethoxazole,atovaquone, clindamycin, pyrimethamine, spiramycin, diminazine,homidium, suramin, melarsamine, sodium stibogluconate and meglumineantimoniate.

Treatment of viral infections with nitazoxanide is known in the art. Thepresent methods provide for the treatment of a subject suffering from aviral infection comprising administering to the subject in need thereofa therapeutically effective amount of a compound or composition of thepresent disclosure. In one embodiment, the pharmaceutical composition isadministered in an amount of 300 to 600 mg or 300, 350, 400, 450, 500,550, or 600 mg of a compound of the present disclosure once a day ortwice a day or three times a day. Treatment regimens may be adjustedbased on the knowledge of one of ordinary skill. For example, thetreatment regimen may be carried out over 1, 2, 3, 4, 5, 6, 7 days or 1,2, 3, or 4 weeks. In one embodiment, the treatment of a subjectsuffering from a viral infection comprising administering to the subjectin need thereof a therapeutically effective amount of a compound orcomposition of the present disclosure provides increased bioavailabilityor better absorption or with of the side effects than a comparativetreatment with nitazoxanide.

The viral infection may be a RNA virus or a DNA virus. RNA viruses ofthe present methods include: The Retroviridae: the HumanImmunodeficiency Virus or HIV; the Reoviridae: the Norovirus or NoV; theCalciviridae: the rotavirus or RoV; the Flaviviridae: the Hepatitis CVirus or HCV; the Yellow Fever Virus or YFV; the Japanese EncephalitisVirus or JEV; the Dengue-2 Fever Virus or DEV; the orthomyxoviridae: theInfluenza A Virus or IAV and the Influenza B Virus or IBV; theparamyxoviridae: the Parainfluenza Virus or HPIV and the RespiratoryScyncytial Virus or RSV; the coronaviridae: the Canine Coronavirus orCCoV and the Middle East Respiratory Virus or MERSCoV. In oneembodiment, viral infection may be the MERS coronavirus in cell linesthat express interferons.

DNA viruses of the present methods include: The Hepadnaviridae: theHepatitis B Virus or HBV; the heipesviridae: the Herpes Simplex Virus-1and -2 or HSV-1 and HSV-2; the Varicella Zoster.

In one embodiment, the treatment of the present disclosure is for HIV,HBV, HCV, NoV, RoV, YFV, JEV, DFV, IAV, IBV, HPIV, RSV, CCoV, MERSCoV,HSV-1, HSV-2, VZV.

The viral infection may be an influenza infection or may be caused by avirus selected from H1N1, H2N2, H3N2, H5N1, H7N7, H1N2, H9N2, H7N2,H7N3, and H10N7. In another embodiment, the treatment is of Influenza Avirus including, H1N1-sensitive or oseltamivir resistant, H3N2-sensitiveand oseltamivir or amantadine resistant, H3N2v, H3N8, H5N9, H7N9,H7N9-sensitive and oseltamivir resistant.

In another embodiment, the viral infection is Hepatitis B.

The treatment of a subject suffering from a viral infection or at riskof developing a viral infection comprising administering to the subjectin need thereof a therapeutically effective amount of a compound orcomposition of the present disclosure may be in the form ofmono-administration or co-administration. In one embodiment, thecompound of composition is administered in combination with at least oneadditional component selected from the group consisting of a vaccine,neuraminidase inhibitor, such as Laninamivir, Oseltamivir, Zanamivir orPeramivir, or an immunostimulant, such as Imiquimod or Resiquimod, or anadamantine analogue, or a recombinant sialidase fusion protein, such asFludase or an anti-hepatitis B drug.

In one embodiment, the treatment of a subject suffering from a viralinfection comprising administering to the subject in need thereof atherapeutically effective amount of a compound or composition of thepresent disclosure provides increased bioavailability or betterabsorption or with of the side effects than a comparative treatment withnitazoxanide.

In another particular aspect of the invention, the subject suffers froma cancer. In a different particular aspect of the invention, the subjectis at risk of developing a cancer. In one embodiment, the cancer isleukemia. Preferably, the leukemia is hairy cell leukemia or chronicmyeloid leukemia. In a different aspect of the invention, the cancer ismelanoma. In yet another aspect of the invention, the cancer isnon-Hodgkin lymphoma. In a further aspect of the invention, the canceris renal cell carcinoma. In a further aspect of the invention, thecancer is breast cancer or colon cancer or prostate cancer. In oneparticular embodiment, the prodrug compound of the present disclosurecompound is administered alone. In another particular embodiment of theinvention, the prodrug compound of the present disclosure isadministered in combination with a vaccine, or an immunostimulant, or ananticancer drug. The anticancer drug may include, but is not limited to,ST1571, CGP 74588, 1-β-D-Arabinofuranosylcytosine (Ara-C), doxorbicin,dacarbazine, cisplatin, bleomycin, vincristine, lomustine, vinblastine,carmustine, DTIC, tamoxifen, sunitinib, sorafenib and interferon-α. Inone embodiment, the pharmaceutical composition is administered in anamount of 300 to 600 mg or 300, 350, 400, 450, 500, 550, or 600 mg of acompound of the present disclosure once a day or twice a day or threetimes a day. Treatment regimens may be adjusted based on the knowledgeof one of ordinary skill. For example, the treatment regimen may becarried out over 1, 2, 3, 4, 5, 6, 7 days or 1, 2, 3, or 4 weeks.

In one embodiment, the treatment of a subject suffering from a cancer orat risk of developing a cancer comprising administering to the subjectin need thereof a therapeutically effective amount of a compound orcomposition of the present disclosure provides increased bioavailabilityor better absorption or with of the side effects than a comparativetreatment with nitazoxanide.

In one embodiment, the prodrug compound or composition of the presentdisclosure is administered to a subject in need thereof to stimulate animmune response. The prodrug compound or composition is administered inan immunostimulatory effective in amount. In one embodiment, the prodrugcompound or composition of the present disclosure is administered with avaccine to a subject in need thereof. The subject may be suffering from,or at risk of developing, a viral infection previously disclosed.

In one aspect, the prodrug compound of the present disclosure exhibitsan increased bioavailability compared to an equivalent amount of thesame nonprodrug compound. In some embodiments, the absolutebioavailability (measured by the area under the curve, AUC) uponadministration of a prodrug compound of the present disclosure comparedto the administration of an equivalent amount of the same non-prodrugcompound is increased by about 5%, about 10%, about 15%, about 20%,about 25%, about 30%, about 35%, or about 40%.

In one aspect, the prodrug compound of the present disclosure exhibits adecreased amount of side effects compared to the equivalent amount ofnitazoxanide. In some embodiments, the number of side effects observedupon administration of a prodrug compound of the present disclosurecompared to the administration of an equivalent amount of nitazoxanideis increased by about 5%, about 10%, about 15%, about 20%, about 25%,about 30%, about 35%, or about 40%.

In one embodiment, the prodrug compound of the present disclosure isadministered to a patent in need thereof without food.

In one embodiment, the composition of the present disclosure and theadditional active agent (e.g., an interferon) may be administeredsimultaneously, or separately, at the same time, or in differentcompositions (including in separate compositions that vary in dosageform, release profiles, and the like).

It is to be understood that the description above as well as theexamples that follow are intended to illustrate and not limit the scopeof the invention. Other aspects, advantages and modifications within thescope of the invention will be apparent to those skilled in the art towhich the invention pertains.

WORKING EXAMPLES

Example 1

Example 2. Synthesis of(S)-[2-[(5-nitro-1,3-thiazol-2-yl)carbamoyl]phenyl]-2-amino-3-methylbutanoate,hydrochloride Part 1:(S)-[2-[(5-nitro-1,3-thiazol-2-yl)carbamoyl]phenyl]-2-(t-butoxycarbonyl)amino-3-methylbutanoate

A mixture of t-butoxycarbonyl-L-valine (Boc-Val-OH; 0.21 g, 0.97 mmol)and tizoxanide (0.25 g, 0.94 mmol) was stirred at 20° C. in anhydrousTHF (7.5 mL). HATU (viz.O-(7-Azabenzotriazole-1-yl)-1,1,3,3-tetramethyluroniumhexafluorophosphate; 0.38 g, 1 mmol) was added in one portion, followedafter 1 h by 4-dimethylaminopyridine (DMAP; 0.12 g, 1 mmol). After 20 h,the mixture was filtered through Celite and the precipitate washed withfurther THF then diluted with ethyl acetate (25 mL). The combinedfiltrate and washings were washed with 7% aq. citric acid, saturated aq.NaHCO₃, water and brine, then dried over anhydrous Na₂SO₄. Evaporationafforded a yellow foam which was chromatographed on silica gel, beingapplied in CH₂Cl₂ and eluted with 1:1 ethyl acetate:hexane. Appropriatefractions were combined and evaporated to afford the title compound as awhite solid (280 mg); ¹H NMR (400 MHz, CDCl₃) δ_(H) 1.03, 1.12 (6H, 2d,Me₂CH), 1.40 (9H, s, Me₃CO), 2.35 (1H, m, Me₂CHCH), 4.39 (1H, m,CHCHNH), 5.20 (1H, m, NH), 7.40 (1H, d, ArH), 7.45 (1H, t, ArH), 7.67(1H, t, ArH), 8.06 (1H, d, ArH), 8.18 (1H, s, thiazole 4-H) and 11.10(1H, br s, NH); m/z (Electrospray +ve mode) 487 (MNa⁺, base peak).Found: m/z, 487.1265. C₂₀H₂₄N₄O₇S requires m/z, 487.1263.

Part 2:(S)-[2-[(5-nitro-1,3-thiazol-2-yl)carbamoyl]phenyl]-2-amino-3-methylbutanoate,hydrochloride

The preceding Boc derivative (0.250 g, 0.54 mmol) dissolved in CH₂Cl₂ (5mL) was treated with 4M HCl in dioxan (2.5 mL) and stirred at 20° C. for20 h. Much solid had already precipitated, and after adding diethylether (Et₂O, 10 mL) and stirring for a further 0.5 h, the precipitatewas filtered off, washed with Et₂O and dried in vacuo to afford thetitle compound (0.220 g) as a very light yellow solid; ¹H NMR [400 MHz,(CD₃)SO] δ_(H) 1.05 (6H, 2d, Me₂CH), 2.37 (1H, m, Me₂CHCH), 4.17 (1H, m,CHCHNH), 7.49 (1H, d, ArH), 7.53 (1H, t, ArH), 7.76 (1H, t, ArH), 7.90(1H, d, ArH), 8.74 (1H, s, thiazole 4-H), 8.80-8.90 (3H, br s, H3N⁺) and13.80 (1H, br s, NH; m/z (Electrospray +ve mode) 387 (MNa⁺ of the freeamine, base peak). Found: m/z, 387.0722. C₁₅H₁₆N₄O₅SNa requires m/z,387.0739.

Example 3. Synthesis of(S)-[2-[(5-nitro-1,3-thiazol-2-yl)carbamoyl]phenyl]-2-amino-3,3-dimethylbutanoate,hydrochloride Part 1:(S)-[2-[(5-nitro-1,3-thiazol-2-yl)carbamoyl]phenyl]-2-(t-butoxycarbonyl)amino-3,3-dimethylbutanoate

A mixture of t-butoxycarbonyl-L-tert-leucine (Boc-Tle-OH, 0.23 g, 1mmol) and tizoxanide (0.26 g, 1 mmol) was stirred at 20° C. in a mixtureof anhydrous THF (10 mL) and anhydrous DMF (4 mL), then treated withN-ethyl-N′-3-(dimethylamino)propyl carbodiimide.HCl (EDC; 0.19 g, 1mmol) and DMAP (0.12 g, 1 mmol). After 26 h the mixture was worked up asdescribed in Example 1 to give crude product as a yellow foam (0.260 g);¹H NMR (400 MHz, CDCl₃) δ_(H) 1.15 (9H, s, Mc₃CC), 1.38 (9H, s, Mc₃CO),4.25 (1H, d, CHNH), 5.22 (1H, br d, CHNH), 7.40-7.50 (2H, m, ArH), 7.67(1H, t, ArH), 8.09 (1H, d, ArH), 8.26 (1H, s, thiazole 4-H) and 11.10(1H, br s, NH); m/z (Electrospray +ve mode) 501 (MNa⁺, base peak).Found: m/z, 501.1417. C₂₁H₂₆N₄O₇SNa requires m/z, 501.1420.

Part 2:(S)-[2-[(5-nitro-1,3-thiazol-2-yl)carbamoyl]phenyl]-2-amino-3,3-dimethylbutanoate,hydrochloride

The preceding Boc derivative (0.254 g, 0.53 mmol) was suspended inCH₂Cl₂ (5 mL) and 4M HCl in dioxan (2 mL) was added with stirring at 20°C. A solution resulted after a few minutes, but solid soon began toprecipitate. After 16 h, the reaction was worked up as described forExample 1 to afford the title compound (0.205 g); ¹H NMR [400 MHz,(CD₃)SO] δ_(H) 1.10 (9H, s, Me₃C), 4.00 (1H, s, CHNH₃ ⁺), 7.54 (1H, d,ArH), 7.62 (1H, t, ArH), 7.75 (1H, t, ArH), 7.85 (1H, d, ArH), 8.73 (1H,s, thiazole 4-H), 8.86 (3H, br s, NH₃) and 13.85 (1H, br s, NH); ¹³C NMR[100 MHz, (CD₃)SO] δ_(C) 26.6, 33.9, 61.5, 124.0, 126.6, 127.1, 130.0,133.7, 142.6, 143.0, 147.8, 162.2, 165.8 and 167.5; m/z (Electrospray+ve mode) 379 (base peak, ammonium ion). Found: m/z, 379.1060.C₁₆H₁₉N₄O₅S requires m/z, 379.1076.

Example 4

Two groups of three male Sprague-Dawley rats were administered RM-5061as a single oral or bolus intravenous dose as detailed in the tablebelow:

# of Route of Targeted Targeted Targeted Animals Adminis- Dose Conc.Dose Vol. Dose Level Group # and Sex tration (mg/mL) (mL/kg) (mg/kg) 1 3M PO 6 5 30 2 3 M IV 5.42 1.11 6

Serial blood samples were obtained from each animal at 0.083, 0.167,0.25, 0.5, 1, 2, 4, 8, 12, and 24 hours post-dose. Pharmacokineticparameters for tizoxanide and tizoxanide glucuronide following a singleoral or a single intravenous dose of RM-5061 are summarized in the tablebelow.

RM-5061 dose C_(max) T_(max) AUC_(last) AUC_(0-inf) T_(1/2,e) Route(mg/kg) Analyte (μg/mL) (hr) (μg*hr/mL) (μg*hr/mL) (hr) F PO 28.0 ±0.75  Tizoxanide  6.19 ± 0.786 0.167 ± 0.0835 3.12 ± 0.347 3.17 ± 0.3330.554 ± 0.3634 0.13 ± 0.0150 (2.7) (12.7) (50.1) (11.1) (10.5)  (65.6)(11.1) Tizox. 18.6 ± 2.83 0.5 ± 0.00 21.4 ± 4.71  23.6 ± 4.52  1.01 ±0.45  glucuronide (15.2)  (0.0) (22.0) (19.2) (44.8) IV 6.30 ± 0.145Tizoxanide 12.8 ± 4.33 0.083 ± 0.000  5.21 ± 2.757 6.31 ± 4.585 0.381 ±0.1341 (2.3) (33.9)  (0.0) (52.9) (72.7) (35.2) Tizox.  7.89 ± 1.8240.75 ± 0.433 13.4 ± 10.40 17.6^(a) 1.27^(a) glucuronide (23.1) (57.7)(77.6) Mean ± SD (% RSD); N = 3 ^(a)Mean of two.

Following oral dose administration of RM-5061 at ˜28 mg/kg, tizoxanidewas detected in the plasma as early as the first blood samplingtimepoint of 0.083 hours in all three animals. The greatest plasmaconcentration of tizoxanide following oral administration of RM-5061occurred between 0.083 and 0.25 hours post-oral dose. The lastquantifiable tizoxanide plasma concentration for the three animalsoccurred at 2 and 4 hours post-oral dose. Mean tizoxanide plasmaelimination half-life was 0.55 hours. Tizoxanide was quickly metabolizedto its glucuronide. Tizoxanide glucuronide was detected in plasma in thefirst blood sampling timepoint of 0.083 hours. Maximum tizoxanideglucuronide plasma concentrations were observed at 0.5 hours post-oraldose, Tizoxanide glucuronide Cmax values were approximately 3-4 timesgreater than tizoxanide Cmax values. Tizoxanide glucuronide AUC valueswere −5-8 times greater than tizoxanide AUC values which suggested rapidglucuronidation. Mean tizoxanide glucuronide T_(1/2,e) was 1.01 hours.An estimate of the oral bioavailability of tizoxanide was low, ˜13%,which was more consistent with its rapid metabolism to tizoxanideglucuronide than the extent of absorption of the prodrug RM-5061 and itsconversion to tizoxanide.

Following intravenous dose administration of RM-5061 at ˜6.3 mg/kg,tizoxanide was detected in the plasma at the first blood samplingtimepoint of 0.083 hours. The greatest plasma concentration oftizoxanide following intravenous administration of RM-5061 occurred atthe first blood sampling timepoint of 0.083 hours. The last quantifiabletizoxanide plasma concentration for the three animals occurred at 1 and2 hours post-intravenous dose. Mean tizoxanide plasma eliminationhalf-life was 0.38 hours. Tizoxanide was quickly metabolized to itsglucuronide. Tizoxanide glucuronide was detected in plasma in the firstblood sampling timepoint of 0.083 hours. Maximum tizoxanide glucuronideplasma concentrations were observed at 0.25 and 1 hour post-intravenousdose.

Tizoxanide glucuronide Cmax values were slightly less than tizoxanideCmax values. Tizoxanide glucuronide AUC values were −2 to 7 timesgreater than tizoxanide AUC values in two of three animals. Individualtizoxanide glucuronide T_(1/2,e) values were 0.55 and 2 hours; in Rat1287, the terminal elimination phase in plasma was not observed since itwas found dead at 2 hours post-intravenous dose. One should note thatthe tizoxanide plasma concentrations of Rat 1287 were greater than thoseconcentrations of the other two animals over the 0.083 to 1 hourtimeframe.

Compared to a similar study for Nitazoxanide, where the respective drugswere administered orally by gavage at a dose of ˜30 mg/kg to rats, andthe oral formulation of each drug was prepared at a concentration of 6mg of drug/ml of vehicle (0.5% carboxymethylcellulose in water), andwhere the nitazoxanide study used 3 male rats and 3 females while theRM-5061 study used 3 male rats, and comparing pharmacokineticsparameters for males to males, the mean maximum plasma concentrations(Cmax) of the tizoxanide metabolite were 6.19±0.786 μg/ml following oraladministration of RM-5061 compared to only 0.454±0.0895 μg/ml followingoral administration of nitazoxanide (a 13.6-fold increase). The meanCmax of the tizoxanide glucuronide metabolite were 18.6±2.83 ng/mlfollowing oral administration of RM-5061 compared to only 3.49±1.089ng/ml following oral administration of nitazoxanide (a 5.33-foldincrease). Importantly, the % Relative Standard Deviation (% RSD) forthe Cmax values were lower following oral administration of RM-5061(12.7% for tizoxanide Cmax and 15.2% for tizoxanide glucuronide Cmax)compared to those following oral administration of nitazoxanide (19.7%for tizoxanide Cmax and 31.2% for tizoxanide glucuronide Cmax). Thesedata indicate that RM-5061 administered orally delivers much higherconcentrations of tizoxanide and tizoxanide glucuronide, and theabsorption is associated with less variability. One of the problemsassociated with nitazoxanide in humans is that its absorption is highlyvariable and that it must be administered with food to improveabsorption (approximately doubled with food). This data suggests thatRM-5061 will deliver higher plasma concentrations of tizoxanide (theactive metabolite) with less variability and perhaps without requiringco-administration with food.

Example 5

Patents are administered the compound of Example 1 orally at 300, 400 or500 mg twice per day for one week. A control group is administered anequivalent amount if nitazoxanide orally at 300, 400 or 500 mg twice perday for one week. Plasma levels of active tizoxanide are monitored inall patient populations during the administration. The bioavailabilityof the administered agent increases in the patient population receivingthe compound of Example 1 in relation to the patient populationreceiving nitazoxanide.

1.-42. (canceled)
 43. A compound having formula:

or a pharmaceutically acceptable salt thereof.
 44. A pharmaceuticallyacceptable salt of the compound of claim
 43. 45. The salt of claim 44,which is a hydrochloric salt.
 46. A pharmaceutical compositioncomprising the compound of claim 43 or its pharmaceutically acceptablesalt.
 47. The pharmaceutical composition of claim 46, wherein thecomposition is an injectable formulation.
 48. The pharmaceuticalcomposition of claim 46, wherein the composition is an intravenousformulation.
 49. The pharmaceutical composition of claim 47, comprisingan aqueous solution of the compound or its pharmaceutically acceptablesalt.
 50. The pharmaceutical composition of claim 46 in a dosage formsuitable for injection.
 51. The pharmaceutical composition of claim 50,wherein the dosage form is suitable for intravenous administration. 52.The pharmaceutical composition of claim 46, wherein the composition isan oral formulation.
 53. A pharmaceutical formulation comprising anaqueous solution of the compound of claim 43 or its pharmaceuticallyacceptable salt.